The Hubbard Brook Ecosystem Study: Forest Biomass and Production

A small watershed in the White Mountains of New Hampshire bearing meso- phytic, cool-temperate, broadleaf-deciduous forests was studied. Acer saccharum, Betula lutea, and Fagus grandifolia are dominant, but toward higher elevations Picea rubens and A bies balsamea also occur and indicate the transition toward subalpine climate. The stands are young (following cutting in 1909-17) but contain older trees; stand composition is thought reasonably representative of the climax. For application of the Brookhaven system of forest dimension analysis, 93 sample trees of major species were cut and roots excavated. Mean dimensions of sample trees, and the constants for the system of logarithmic regressions relating volume, surface, mass, and growth to diameter at breast height and other independent vari- ables, show decrease in tree sizes and height/diameter ratios toward higher elevations. Stand characteristics, based on application of the regressions to forest samples, show trends of decrease for the elevation belts from low to high: stem basal area 26.3, 23.7, and 22.0 m2/ha, weighted mean tree height 16.9, 16.7, and 10.8 m, weighted mean age 124, 95, and 83 yr, stem wood volume 176, 155, and 103 m3/ha, aboveground biomass (dry matter) 162, 152, and 102 t/ha, estimated volume increment 379, 365, and 223 cm3/m2/yr, aboveground net primary productivity (1956-60) 1127, 1041, and 790 g/m2/yr, and leaf area ratio 6.2, 5.7, and 5.5 m2/m2. Biomass (and, presumably, production) of root systems is 18%-21% of that aboveground. Different estimations suggest that a mean climax biomass for the watershed may be around 350 t/ha, aboveground. Net ecosystem production (i.e., addition to the pool of woody biomass in the community) is estimated as 350 g/m2/yr aboveground and 85 below- ground for 1956-60, 238 and 52 g/m2/yr for 1961-65. Analysis of stem wood volume incre- ments reveals an abrupt and striking (18%) decrease in volume growth and productivity from 1956-60 to 1961-65. The net primary productivity of the former period, with a weighted mean for the watershed of 1110 g/m2/yr above and below the ground, is thought more nearly normal for the forest. Both drought and effects of increasing air pollution (notably increasing acidity of rainfall) may be responsible for the recent decrease in productivity.

[1]  G. Likens,et al.  OUTPUT OF PHOSPHORUS, DISSOLVED ORGANIC CARBON, AND FINE PARTICULATE CARBON FROM HUBBARD BROOK WATERSHEDS1 , 1973 .

[2]  P. Sollins,et al.  Carbon flow and storage in a forest ecosystem. , 1973, Brookhaven symposia in biology.

[3]  C. Federer.  Annual cycles of soil and water temperatures at Hubbard Brook , 1973 .

[4]  G. Likens,et al.  Nutrient Content of Litter Fall on the Hubbard Brook Experimental Forest, New Hampshire , 1972 .

[5]  F. Bormann,et al.  Revegetation following Forest Cutting: Mechanisms for Return to Steady-State Nutrient Cycling , 1972, Science.

[6]  J. R. Wallis,et al.  Some ecological consequences of a computer model of forest growth , 1972 .

[7]  W. Reiners.  Structure and Energetics of Three Minnesota Forests , 1972 .

[8]  C. Federer,et al.  Streamflow Changes after Forest Clearing in New England , 1970 .

[9]  Gene E. Likens,et al.  Effects of Forest Cutting and Herbicide Treatment on Nutrient Budgets in the Hubbard Brook Watershed-Ecosystem , 1970 .

[10]  G. Likens,et al.  The Hubbard Brook Ecosystem Study: Composition and Dynamics of the Tree Stratum , 1970 .

[11]  G. Likens,et al.  Nutrient cycling in ecosystems. , 1970 .

[12]  R. Bunce,et al.  Fluctuations in litter-fall in a mixed deciduous woodland over a three-year period 1966-68 , 1970 .

[13]  G. Likens,et al.  A Working Model for the Variation in Stream Water Chemistry at the Hubbard Brook Experimental Forest, New Hampshire , 1969 .

[14]  G. Likens,et al.  Biotic regulation of particulate and solution losses from a forest ecosystem , 1969 .

[15]  G. Likens,et al.  Nitrification: Importance to Nutrient Losses from a Cutover Forested Ecosystem , 1969, Science.

[16]  George M. Woodwell,et al.  Structure, Production and Diversity of the Oak-Pine Forest at Brookhaven, New York , 1969 .

[17]  G. Likens,et al.  Response of Chemoautotrophic Nitrifiers to Forest Cutting , 1968 .

[18]  G. Likens,et al.  Atmospheric Contributions to Water Quality of Streams in the Hubbard Brook Experimental Forest, New Hampshire , 1968 .

[19]  G. Likens,et al.  Rate of chemical weathering of silicate minerals in New Hampshire , 1968 .

[20]  G. M. Woodwell,et al.  DIMENSION AND PRODUCTION RELATIONS OF TREES AND SHRUBS IN THE BROOKHAVEN FOREST, NEW YORK. , 1968 .

[21]  G. Likens,et al.  Nutrient Loss Accelerated by Clear-Cutting of a Forest Ecosystem , 1968, Science.

[22]  J. Wehrmann.  Rodin, L. E., und Bazilevich, N. J.: Production and Mineral Cycling in Terrestrial Vegetation (Übersetzung aus dem Russischen von G. E. Fogg). Oliver and Boyd, Edinburgh und London 1967. 288 Seiten, 69 Abbildungen und 57 Tabellen, £ 7, 7s , 1968 .

[23]  P. Newbould,et al.  Methods of Estimating the Primary Production of Forests. , 1968 .

[24]  G. M. Woodwell,et al.  SURFACE AREA RELATIONS OF WOODY PLANTS AND FOREST COMMUNITIES , 1967 .

[25]  N. I. Bazilevich,et al.  Production and mineral cycling in terrestrial vegetation , 1967 .

[26]  T. Kira,et al.  Comparative ecological studies on three main types of forest vegetation in Thailand. II. Plant biomass , 1965 .

[27]  Eville Gorham,et al.  Litter Production in Forests of the World , 1964 .

[28]  J. Ovington.  Quantitative Ecology and the Woodland Ecosystem Concept , 1962 .

[29]  J. R. Bray.  Measurement of Leaf Utilization as an Index of Minimum Level of Primary Consumption , 1961 .

[30]  Robert H. Whittaker,et al.  Vegetation of the Great Smoky Mountains , 1956 .

[31]  R. E. Shanks.  Climates of the Great Smoky Mountains , 1954 .